This article originally appeared in the May/June 1999 issue of the ASTC Newsletter.

Giving visitors an appreciation for the vastness of the universe is the aim of a growing collection of true-scale solar system models that map our solar neighborhood within the bounds of city limits, or in some cases, counties and states. From Peoria, Illinois to St.-Luc, Switzerland, a number of science centers, planetariums, and civic groups have installed accurately scaled representations of the sun and planets. Several new community solar system projects are in the works.

In depicting both the sizes and distances of the planets, these planetary exhibition projects are necessarily spread out-even the smallest of them requires a space longer than two football fields to locate a pinpoint-sized Pluto. Because planet placement requires the support and participation of whole communities, these projects have become great science education outreach vehicles for the institutions involved. A sampler of community solar systems follows.

Projects already in orbitLakeview Museum and Planetarium Community Solar System, Peoria, Ill. Peoria's community solar system, coordinated by planetarium director Sheldon Schafer, has the distinction of being the "largest model of the solar system" in the world as recognized by the Guinness Book of World Records. Using the 36-foot planetarium dome as the diameter of the sun, Peoria's model places finely-painted, three-dimensional planets in buildings and businesses throughout central Illinois. The Earth is a softball-sized orb three-fourths of a mile away, while marble-sized Pluto sits in the town of Kewanee, Illinois, 40 miles away.
Scale factor: 1:140 million
Sun diameter: 11 meters
Earth diameter: 10 cm
Sun-Earth distance: 1.2 km
Sun-Pluto distance: 64 km
Special features: For a small fee, you and your community can become part of the world's largest solar system model. The Lakeview Museum has sent plaques to sites all over the world (including Russia, Japan, Denmark, Swaziland, and the South Pole) registering them as locations for "unnamed comets" that exist far beyond Pluto's orbit.
For more information:http://www.bradley.edu/las/phy/solar_system.html.

Sagan Planet Walk, Ithaca, N.Y. This series of outdoor monuments stretches 1,200 meters from the sun station at Ithaca Commons to Pluto at the Sciencenter. Conceived and developed by Charles Trautmann and Robert Orange of the Sciencenter, the model was dedicated to Carl Sagan, the late astronomer, author, television personality, and Cornell University professor, in November of 1997. Local artist Erin Caruth designed the 2-meter-high granite and concrete monoliths, which feature porcelain-enamel signs illustrated by high-resolution NASA color images of the planets. The scale models of the planets are embedded in scale sun-sized Plexiglas windows in each monument.
Scale Factor: 1:5 billion
Sun diameter: 300 mm
Earth diameter: 2.5 mm
Sun-Earth distance: 30 meters
Sun-Pluto distance: 1,200 meters
Special feature: A nifty "Passport to the Solar System," written by Sagan's wife and long-time collaborator Ann Druyan, is available at the Sciencenter and local businesses. These same businesses will "stamp" your passport as proof of your visit to each planet. A fully stamped passport entitles you to a souvenir button and one free admission to the Sciencenter.
For more information: www.sciencenter.org/SaganPW/.

Scale Model Solar System, Eugene, Ore. This community project started out with a father-son duo-Jack Van Dusen and his son Ben-who decided to create their own model by painting the planets on the ground along a local bike path. A couple of years after that model was washed away by the rain, Van Dusen began an odyssey of grantwriting, fundraising, and problem-solving to create a model that would last. He enlisted the support of private citizens, local businesses and foundations, the Eugene Parks and Planning office, the local school district, and the local planetarium, and Willamette Science and Technology Center.
Scale Factor: 1:1 billion
Sun diameter: 1.39 meters
Earth diameter: 1.28 cm
Sun-Earth distance: 150 meters
Sun-Pluto distance: 5.9 km
Special feature: Jack Van Dusen's odyssey continues, as this model of stainless steel planet spheres on steel pyramids is still in progress. The Eugene Parks Office is still seeking funding to augment the solar system with informational displays.
For more information: http://www.efn.org/~jack_v/.

Museum of Science Community Solar System, Boston, Mass. Boston's scale model solar system opened in October 1997 as part of a permanent astronomy exhibition called Welcome to the Universe. Exhibit developers Mary Dussault and Deborah Sovinee wanted the scale to be large enough so "Pluto was at least the size of a pea," but small enough so that the whole solar system was within reach of public transportation. The resulting model starts with a 3.6 meter fiberglass hemisphere of the sun in the Welcome to the Universe exhibition. The nine planets are cast in bronze from molds sculpted with tactile surface details by museum preparator Richard Sheffield. Supported by laser-cut steel bases, the planets are located in shopping malls, libraries, transit stations, and other public spaces in and around metropolitan Boston.
Scale factor: 1:400 million
Sun diameter: 3.6 meters
Earth diameter: 3.2 cm
Sun-Earth distance: 390 meters
Sun-Pluto distance: 15 km
Special feature: At the museum, duplicates of the 9 bronze planets are arranged around the sun with audio labels, making the size scale of the solar system completely accessible to blind visitors.
For more information: www.mos.org/sln/wtu/css.html.

Francois-Xavier Bagnoud Observatory Scale Solar System, St.-Luc, Switzerland. This Alpine planet walk uses two different scales for the distances and diameters of the planets: the two-hour hike from Sun to Pluto is about 6 kilometers, while the aluminum ball planets are about 10 times larger than they would be if kept to scale. Hikers and astronomy enthusiasts are treated to spectacular views of the Swiss Alps, including the Matterhorn, as they start out from the base of an amateur astronomical observatory. Each planet site contains a piece of modern art, designed by Swiss artist Jacques Zufferey.
Scale factors: 1:1 billion (distance); 1:100 million (diameter)
Sun Diameter: 14 meters
Earth diameter: 12.7 cm
Sun-Earth distance: 150 meters
Sun-Pluto distance: 5.9 km
Special feature: During the summer, the St.-Luc tourist office offers guided tours and rents audio headsets for the outdoor exhibits. During the winter months you can ski or snowshoe through the solar system.
For more information:http://www.ofxb.ch/.

Projects on the launch padSolar System Walk, Gainesville, Fla. This February, the Gainesville Department of Cultural Affairs announced a "Call to Artists" for the design and creation of a one to four billion scale model of the Solar System. The project was initiated by the Gainesville City Commission, in collaboration with the Alachua Astronomy Club.

The Voyage Project, Washington D.C. The Challenger Center for Space Science Education, the Smithsonian Institution, and the National Aeronautics and Space Administration are collaborating to develop a one to ten billion scale model solar system as a permanent exhibition for the National Mall. Plans currently call for designing the planetary components so they can be easily replicated and placed at science centers and communities around the world.

As kinesthetic, non-verbal, meaningful quantitative experiences, scale model solar systems and planet walks are ideal projects for science centers. It's one thing to calculate or memorize that the earth is 150 million kilometers from the Sun, but it's quite another to walk and feel that distance in three-dimensional space.